1. Field of the Invention
The present disclosure relates to a structure of a crossbar for a manual motor starter, and particularly, to a structure of a crossbar for a manual motor starter in which a function of an auxiliary lever is performed by a crossbar to thus reduce the number of components and an operational error.
2. Background of the Invention
In general, a manual motor starter (MMS), a device used in an electric line in which a rated insulation voltage is alternating current (AC) 690V (frequency 50 Hz or 60 Hz), is installed in a front stage of a motor to operate in the event of an fault current such as an overcurrent, phase loss, phase reverse, a short circuit, and a ground fault to break a system in order to protect the system and a load device.
The MMS includes a detecting unit for detecting a fault current such as an overcurrent, phase loss, phase reverse, a short circuit, and a ground fault in the occurrence thereof, an operating mechanism for tripping a circuit breaker according to a detection signal from the detecting unit, a contact unit cooperatively operated according to an operation of the operating mechanism to open and close an electric line, and an arc extinguishing unit extinguishing an arc generated as contacts of the contact unit are separated and discharging the same to the outside. Also, an auxiliary contact unit for sending a control signal to an accessory device according to an operation of the operating mechanism is also provided.
In the MMR, during normal conduction, a movable contact and a fixed contact of the contact unit are connected and a current flowing into a power source side terminal is allowed to flow to a load side terminal, but when a fault current occurs, the detecting unit detects the fault current and drives the operating mechanism, the movable contact of the movable contact arm is separated from a fixed contact of a fixed contact arm to cut off the current flowing to the load side.
FIG. 1 is a perspective view of an MMS according to the related art, and FIG. 2 is a vertical cross-sectional view illustrating an operational state of the MMR according to the related art in which a handle is in an ON state, viewed in a lateral direction.
The MMR according to the related art includes a crossbar 1, an auxiliary lever 2, a mechanism assembly 3, an auxiliary contact lever 4, and handle 6.
The MMR according to the related art operates as follows.
When the handle 6 is in an OFF state, the crossbar 1 is lowered by the mechanism assembly 3, and a connection member 7 connected thereto presses the movable contact arm 9 downwardly, and thus, the movable contact arm 9 is separated from the fixed contact arm 8 and a current does not flow in the circuit. Also, when the crossbar 1 is lowered, the auxiliary lever 2 is also in a lowered position, and thus, the auxiliary lever 2 cannot operate the auxiliary contact lever 4 and the auxiliary contact 5 is in a separated state.
When the handle 6 is rotated from the OFF position to an ON position, the mechanism assembly 3 operates and the crossbar 1 is released from a pressed state and moves up. Accordingly, the movable contact arm 9 of the contact unit is lifted to come into contact with the fixed contact arm 8 to make conduction. Also, the crossbar 1 lifts the auxiliary lever 2 and the auxiliary contact lever 4 is cooperatively lifted to come into contact with the auxiliary contact 5 to operate it.
In the MMR according to the related art, in order to operate the auxiliary contact 5, the auxiliary lever 2 is essential.
However, in the related art, the auxiliary lever 2 is a component serving to lift the auxiliary contact lever 4 to simply operate the auxiliary contact 5, and a function thereof limited.
Thus, the use of the auxiliary lever 2 as a separate component to operate the auxiliary contact 5 degrades assembly characteristics, and also, due to a defect of the auxiliary lever 2 or a defective assembly of the auxiliary lever 2, the auxiliary lever 2 may not normally push up the auxiliary contact lever 4 to cause defective conduction of the auxiliary contact 5.